Next here to the landmark ruling by the supreme court today that could affect millions of women who are concerned about breast cancer. You may remember a few weeks ago actress angelina jolie underwent a double mastectomy after a test showed she carried a gene mutation that increases her chance of breast cancer. Tonight it allows researchers to develop similar tests. Reporter: Just 11 days before today's landmark supreme court ruling, angelina jolie walked the red carpet, her story and so many others tide up with this case. I feel great. I feel wonderful. Reporter: In february, jolie underwent a preventative double mastectomy, because she carries a defective gene that dramatically escalates the risk of breast cancer and ovarian cancer. Jolie's mom and her aunt died of breast cancer, and doctors told her she had an 87% chance of developing the disease herself. Hundreds of thousands of americans carry that same gene. And until today, one company, myriad again et iks of california, owned that gene. That's right, they owned it, because they had done the work and spent the money to identify and locate it among the roughly 20,000 genes that every person has. The question before the court, can you really own a part of a person? In a unanimous decision the court said no, justice clarence thomas writing, myriad did not create anything. Now doctors and researchers say the cost of getting tested for that gene will likely come down, from about $3,000 today since other companies will be able to compete with myriad. And most important, the ruling applies to all of our genes, which means scientists will be able to explore all of them without the fear of corporate control. Terry moran, abc news, washington. I want to bring in dr. Jennifer ashton. Jenn, you were watching this closely today. As a doctor, what did you read into the ruling? This company will no longer have a lock on tests like this. They will be lots of different ones, hopefully more research and more access to testing. We need to remember this test and mutation does not just affect women. You are just as likely to be affected as a man. As an obyn I say do you have a father, brother, son, higher risks of prostate cancer and breast cancer. They too should be tested. Just a few seconds left, costs, if there are more tests does it bring the costs down. Mike: Absolutely. Don't let cost stop you from getting tested. Tonight to the whistle blower making global headlines

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